A randomised trial was undertaken to compare the effect of three oral care protocols in delaying the onset of stomatitis and reducing oral injury in nasopharyngeal cancer patients undergoing radiotherapy, 30 eligible patients with a mean age of 56.2 years were recruited and evenly allocated to one of the three groups using a randomly permuted blocks method. Patients allocated to group E1 and group E2 were given the same instructions on oral care at 1 day, and 1 week before radiotherapy, respectively, while those allocated to the control group were given no instructions. We use the Oral Assessment Guide to assess the oral physical conditions of these patients daily. Our findings revealed that the patients in the E2 group not only had later onset of stomatitis than those in the control and the E1 groups, but also had lesser degree of oral injury measured by the overall assessment score. We thereby recommend the use of the E2 protocol for delaying the onset of stomatitis and reducing oral injury in nasopharyngeal cancer patients undergoing radiotherapy.